Catalytic-activity rate (cat.rate) - Dynamic NPU Manual

Catalytic-activity rate (cat.rate)



Definition in words

Change in catalytic-activity of component B divided by the elapsed time

Note: Component B is a catalytic component.

Definition by equation

Systematic terms

Catalytic-activity rate of component B in system 1

Result type

Rational scale
  • Value sets are positive numerical values
  • Algebraic operations are allowed (a=nb; a≠nb)
Numerical values from 0-∞


µkat/second, µkat/day, U/day, U/second, etc.

Note 1: Katal (abbreviated “kat”), is recommended unit for catalytic-activity kind-of-quantity. (katal=mol/s)

Note 2: Enzyme unit (abbreviated “U”) is acceptable for use (e.g. U, kU) but it is recommended to use katal. (Enzyme unit=µmol/min)

Special rule(s) in the NPU syntax

The catalytic component (component B) is termed according to the International Enzyme Nomenclature (see Medical and metrological vocabulary).

“Procedure” is stated in the specification to the kind-of-property in the NPU definition.

“Procedure” indicates that the measurement procedure must be stated somewhere else than the NPU code and there may be difficulties in comparing values for the same NPU code.


Ferard G, Dybkaer R, Fuentes-Arderiu X. Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences : Recommendations 2016. 1 ed: Royal Society of Chemistry; 2016. 182 p. Doi:10.1039/9781782622451.


Laboratory field


Clinical Chemistry

Example 1
Generic abbreviated form NPU01241 Pancreas—Amylase production; cat.rate(37 °C; proc.) = ? µkat/s
Full form with a result NPU01241 Pancreas—Amylase production; catalytic-activity rate(37 °C; procedure) = 18 microkatal per second
Abbreviated form with a result NPU01241 Pancreas—Amylase production; cat.rate(37 °C; proc.) = 18 µkat/s
Written expression The catalytic-activity rate of Amylase production in Mr. Smith’s pancreas is [18] µkat/s. The measurement is performed at 37 °C according to a procedure defined by the laboratory.

Molecular Biology and Genetics

Example 2
Generic abbreviated form NPU54970 Pt(U)—Amylase; cat.rate(IFCC 2006) = ? U/d
Full form with a result NPU54970 Patient(Urine)—Amylase; catalytic-activity rate(IFCC 2006) = 25 Enzyme unit per day
Abbreviated form with a result NPU54970 Pt(U)—Amylase; cat.rate(IFCC 2006) = 25 U/d
Written expression The catalytic-activity rate of Amylase in Mr. Smith’s urine is [25] U/d. The measurement is performed at 37 °C according to procedure defined by IFCC in 2006.

Notes Schumann, G., Aoki, R., Ferrero, C., et al. (2011). IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C: International Federation of Clinical Chemistry and Laboratory Medicine (IFCC): Scientific Division, Committee on Reference Systems for Enzymes (C-RSE): Part 8. Reference procedure for the measurement of catalytic concentration of α-amylase: [α-Amylase: 1,4-α-D-glucan 4-glucanohydrolase (AMY), EC]. Clinical Chemistry and Laboratory Medicine (CCLM), 44(9), pp. 1146-1155. Retrieved 16 Aug. 2019, from doi:10.1515/CCLM.2006.212


NPU database, and
  • Kind-of-property

    • Nominal kind-of-property

    • Kind-of-quantity

      • Ordinal kind-of-quantity

      • Unitary kind-of-quantity

        • Rational unitary kind-of-quantity

          • Catalytic-activity rate


  • Dybkaer R. Concept system on ‘quantity’: formation and terminology. Accredit Qual Assur. 2013;18(3):253-60.
  • Dybkaer R. ISO terminological analysis of the VIM3 concepts ‘quantity’ and ‘kind-of-quantity’. Metrologia. 2010;47(3):127-34.
Date Term Note
1996-01-01 Catalytic-activity rate Term established